The Tahe oilfield located in the southwest of the Akkol uplift in the northern Tarim basin is a large-scale oilfield of karst-fractured reservoir in Lower Ordovician carbonate rocks and was formed under the background of a long developed palaeo-uplift. Controlled by regional tectono-sedimentary setting, the Tahe area in the Early Ordovician was in an open carbonate platform environment and in an inherited uplift. For a long time, it was the targeted area of oil/gas migration and accumulation, and underwent multi-episode tectonic movements, karstification and diagenesis. The karst-fractured reservoir presents the characteristics of intense anisotrope and lowest matrix porosity/permeability. Oil and gas are mostly accumulated in the caves and fracture system of the karst-buried hills within the bed of 200 meters below the weathered unconformity. Exploration practices indicate that the formation of the Tahe oil reservoir was controlled by long-term developed, inherited palaeo-uplift, rich-supply sources, intensive anisotropic karst-fractured reservoir and good caprock associations, widely developed traps of different types, and the conduit system consisting of karst palaeo-hill fractures and pore spaces and unconformity surfaces.